1. Field of the Invention
The present invention relates to a burner for a heat generator.
2. Discussion of Background
Low-pollution combustion of liquid fuels, such as, for example, fuel oil EL (=extra light), requires the complete vaporization of the fuel droplets as well as the premixing of the fuel with the combustion air before the flame front is reached. Even small zones having a higher fuel concentration lead to increased temperatures in the reaction zone and thus to increased formation of thermal nitrogen oxides.
It has become known from the prior art to atomize the oil with various designs of swirl- or air-assisted, central nozzles arranged on the head side of the premix section. However, the atomization quality which can thus be achieved is restricted in various operating modes of these burners. This is essentially connected with the fact that the impulse of the droplet spray formed from the fuel injection turns out to be relatively small, whereby directed introduction of this fuel into certain burner zones is inadequate or not possible at all.
Since the fuel droplets in the case of such a configuration are rapidly decelerated by the combustion air which flows into the premix section, they cannot be readily distributed radially in the inflowing combustion air. The consequence of this inadequate premixing is insufficient vaporization of the injected fuel, which is reflected in the fact that fuel-rich zones form on the burner axis, and these fuel-rich zones are then responsible for causing increased formation of thermal nitrogen oxides in the combustion zone.